A. Field of Invention
This invention concerns a process for the continuous folding of a thin sheet with asymmetric pleats permitting the attainment of high outputs.
B. Description of the Prior Art
Fabric pleating machines are known which have a comb driven in an alternating movement to shape the pleat; this comb slips the end of the pleat between two rollers which press it. Then the pleats can be affixed to one another on all or part of their length by various means such as the attachment of an adhesive tape. These machines can also be used for pleating papers or thin complex sheets with or without a paper base. In France, pursuant to Patent No. FR-2595666-B1, a new technique of wrapping convex bodies has been developed, using thin, pleated compound sheets; the pleats used are asymmetric pleats affixed near their ends along a narrow tape running substantially perpendicular to the folding direction. The problem is that, although these machines have a very great flexibility permitting the production of a small number of sheets, when larger production is involved the rate of production is limited by the movements of the comb. That is because when the rate of production is accelerated, the accelerations and decelerations to which the comb is subjected increase and there is a risk of injuring and even of tearing the sheet being pleated. Hence, there is a need to find a machine operating at a high rate of output which will not treat the sheets aggressively. One of the means for reducing the aggressivity of the pleating device against the sheet is to diminish its relative velocity. This is the reason why the invention to be described makes use of a continuous pleating device.